This invention relates to an electric ironing device and, more particularly, to an electric pressing iron having an improved efficiency and greatly extended life.
In recent years, consumers have demonstrated a strong preference for electric pressing irons capable of producing and discharging steam for facilitating the ironing operation by relaxing so-called stubborn or deep set wrinkles in fabric. These irons normally consist of a cast aluminum sole plate having an electric sheathed heater imbedded therein. Overlying the sole plate is a water tank connected to feed water into a steam generating chamber defined in part by a cavity in the sole plate. Also defined by the sole plate are passageways which connect to a plurality of steam discharge ports in the bottom surface of the sole plate whereby water entering the cavity is converted to steam by the heat supplied by the heater. The steam is discharged through the ports to the material being ironed. A suitable handle is assembled over the tank and normally carries the controls for regulating the temperature of the sole plate as well as means for actuating the steaming operation by controlling the valve disposed in the water conduit between the tank and the sole plate steam generating cavity. In some irons, means are also provided to generate a momentarily, stronger surge of steam. Such means are disclosed in the Gronwick et al U.S. Pat. No. 3,599,357, assigned to the same assignee as the present invention. The surge of steam obtained in irons such as disclosed in the Gronwick et al. patent is further effective in relaxing some of the extremely deep set wrinkles in the fabric.
One of the problems associated with today's steam irons which are often used with fairly hard water, is corrosion within the valve assembly between the water tank or reservoir and the sole plate steam generating cavities. There are also often deposits which form in and around this valve assembly and which affect the efficiency and operation of the steaming process or can also block the passage of water completely. Of the approaches taken to correct this situation, the Downing U.S. Pat. No. 3,675,351 discloses the use of a control valve made completely of ceramic. The approach disclosed in the Downing patent is less satisfactory from the standpoint of reducing deposits and presents problems from a manufacturing and design standpoint. A completely ceramic valve is itself difficult to support because of tolerance problems. Furthermore, it cannot adequately be used as a supporting member between the water reservoir and the sole plate due to the weaker structural properties of ceramic including its tendency to crack and break.
It would thus be desirable to maintain a metallic control valve assembly which can further function as support means and to construct the orifice portion, being the section most susceptible to corrosion and obstructing deposits, of a non-porous, and relatively hard material. Furthermore, by having only the orifice portion made of a separate material it would further be possible to obtain an extremely smooth and hard material such as a synthetic jewel without the cost of having the entire valve structure made up of this relatively expensive material.